The present invention relates to a method and an apparatus for observing with the passage of time the state of a mechanical seal provided on a rotary machine while the rotary machine is being operated.
With a rotary machine in which a mechanical seal is used as a shaft seal, any excessive leakage of sealed fluid due to mechanical seal failure would possibly lead to disasterous results such as fire, environmental pollution or the like, or to halting of plant operations.
Despite this, no effective method has yet materialized for observing readily and with certainty the state of a mechanical seal during operations. Due to this, a troublesome daily tour of inspection has had to be performed in order to spot any mechanical seal trouble at an early stage, or mechanical seals have been changed well before any trouble is likely to occur in order to obviate any mechanical seal trouble. Thus, inspection and maintenance of mechanical seals has required much effort and much expense.
As previously stated, performing a regular inspection as mentioned above involves a high labour cost, and every time inspection of a mechanical seal is performed, the rotary machine has to be halted. In addition, there has been a tendency for mechanical seals to be changed well before their life is over because of the risk of trouble occurring even when it is regarded as being serviceable for a further period, which is of course wasteful.